Powered off the ground by 27 engines, the 227-foot-tall rocket can lift up to 117,000 pounds into low Earth orbit. It is composed of three core stages and a single-engine upper stage based on the Falcon 9 rocket.

SpaceX is finishing development of the huge Falcon Heavy before shipping the first rocket to Vandenberg Air Force Base, Calif., for liftoff on a test flight in mid-2013.

SpaceX is paying for the demonstration flight in 2013 with internal funding.

"Access to space is essential for commercial operators and we want to support a new entrant with reliable products able to launch large spacecraft into [geosynchronous transfer orbit]," Horwitz said in a statement. "We believe SpaceX should be supported in their effort to develop reliable and powerful launch vehicles."

SpaceX spokesperson Kirstin Brost Grantham said the Intelsat mission's launch site has not been determined. The Vandenberg facility under construction for next year's test flight is positioned for launches into polar orbit, while Intelsat and other communications satellite operators deploy spacecraft into orbit over the equator.

SpaceX is considering a former shuttle launch pad at the Kennedy Space Center for future Falcon Heavy missions. The huge booster could also lift off from SpaceX's existing Cape Canaveral pad or a potential private launch site in Florida, Texas, Hawaii, or Puerto Rico.